Perioperative Fluid Management

Abstract

Fluid management is an essential part of postoperative therapy. Fluid administration should be strictly guided by defined physiologic end points and should not follow fixed standards. Relevant end points are a normal arterial blood pressure, heart rate, lactate concentration and urinary output. The measurement of central venous pressure is only a limited monitoring tool. Especially in abdominal surgical patients, central venous pressure (CVP) may be falsely high. A more complex analysis of fluid requirements is necessary in patients simultaneously presenting with an acute or chronic myocardial insufficiency. A subtle clinical and radiological examination of the patient is also essential to identify an impending volume overload. The approximate baseline fluid requirement of an otherwise healthy adult patient during the postoperative phase is usually in the range of 1.0 -1.5 ml kg-1 h-1., but may be significantly higher in severe sepsis or SIRS. Furthermore, after operation potassium requirement is usually increased and sodium requirement decreased. Crystalloid solutions (full strength electrolyte solutions) are the essential component of immediate postoperative fluid therapy. Isotonic sodium chloride solutions are used to correct extracellular fluid deficits, which are combined with hyponatremia, hypochloremia and also with hyperpotassemia. Solutions such as 5% dextrose/ are not appropriate for resuscitation or fluid replacement therapy except in conditions of a significant free water deficit. 5 % dexrose infusion rate should not surmount 1.5 ml kg-1 h-1. None of the colliodal solutions, which are available for postoperative fluid therapy, have proved superior to crystalloid solutions with respect to patient outcome.